/**
* Remove the cache lock, if present.
*
* First, try to close the file handle, whose delete-on-close should
* kill the file. Otherwise, just delete the file by name.
*
* If no lock name has yet been calculated, do the calculation of the
* lock name first before trying to delete the file.
*
* If an optional bucket brigade is passed, the lock will only be
* removed if the bucket brigade contains an EOS bucket.
*/
apr_status_t cache_remove_lock(cache_server_conf *conf,
cache_request_rec *cache, request_rec *r, apr_bucket_brigade *bb)
{
void *dummy;
const char *lockname;
if (!conf || !conf->lock || !conf->lockpath) {
/* no locks configured, leave */
return APR_SUCCESS;
}
if (bb) {
apr_bucket *e;
int eos_found = 0;
for (e = APR_BRIGADE_FIRST(bb);
e != APR_BRIGADE_SENTINEL(bb);
e = APR_BUCKET_NEXT(e))
{
if (APR_BUCKET_IS_EOS(e)) {
eos_found = 1;
break;
}
}
if (!eos_found) {
/* no eos found in brigade, don't delete anything just yet,
* we are not done.
*/
return APR_SUCCESS;
}
}
apr_pool_userdata_get(&dummy, CACHE_LOCKFILE_KEY, r->pool);
if (dummy) {
return apr_file_close((apr_file_t *)dummy);
}
apr_pool_userdata_get(&dummy, CACHE_LOCKNAME_KEY, r->pool);
lockname = (const char *)dummy;
if (!lockname) {
char dir[5];
/* create the key if it doesn't exist */
if (!cache->key) {
cache_generate_key(r, r->pool, &cache->key);
}
/* create a hashed filename from the key, and save it for later */
lockname = ap_cache_generate_name(r->pool, 0, 0, cache->key);
/* lock files represent discrete just-went-stale URLs "in flight", so
* we support a simple two level directory structure, more is overkill.
*/
dir[0] = '/';
dir[1] = lockname[0];
dir[2] = '/';
dir[3] = lockname[1];
dir[4] = 0;
lockname = apr_pstrcat(r->pool, conf->lockpath, dir, "/", lockname, NULL);
}
return apr_file_remove(lockname, r->pool);
}
static char *data_file(apr_pool_t *p, disk_cache_conf *conf,
disk_cache_object_t *dobj, const char *name)
{
if (!dobj->hashfile) {
dobj->hashfile = ap_cache_generate_name(p, conf->dirlevels,
conf->dirlength, name);
}
if (dobj->prefix) {
return apr_pstrcat(p, dobj->prefix, CACHE_VDIR_SUFFIX, "/",
dobj->hashfile, CACHE_DATA_SUFFIX, NULL);
}
else {
return apr_pstrcat(p, conf->cache_root, "/", dobj->hashfile,
CACHE_DATA_SUFFIX, NULL);
}
}
/**
* Try obtain a cache wide lock on the given cache key.
*
* If we return APR_SUCCESS, we obtained the lock, and we are clear to
* proceed to the backend. If we return APR_EEXIST, then the lock is
* already locked, someone else has gone to refresh the backend data
* already, so we must return stale data with a warning in the mean
* time. If we return anything else, then something has gone pear
* shaped, and we allow the request through to the backend regardless.
*
* This lock is created from the request pool, meaning that should
* something go wrong and the lock isn't deleted on return of the
* request headers from the backend for whatever reason, at worst the
* lock will be cleaned up when the request dies or finishes.
*
* If something goes truly bananas and the lock isn't deleted when the
* request dies, the lock will be trashed when its max-age is reached,
* or when a request arrives containing a Cache-Control: no-cache. At
* no point is it possible for this lock to permanently deny access to
* the backend.
*/
apr_status_t cache_try_lock(cache_server_conf *conf, cache_request_rec *cache,
request_rec *r)
{
apr_status_t status;
const char *lockname;
const char *path;
char dir[5];
apr_time_t now = apr_time_now();
apr_finfo_t finfo;
apr_file_t *lockfile;
void *dummy;
finfo.mtime = 0;
if (!conf || !conf->lock || !conf->lockpath) {
/* no locks configured, leave */
return APR_SUCCESS;
}
/* lock already obtained earlier? if so, success */
apr_pool_userdata_get(&dummy, CACHE_LOCKFILE_KEY, r->pool);
if (dummy) {
return APR_SUCCESS;
}
/* create the key if it doesn't exist */
if (!cache->key) {
cache_generate_key(r, r->pool, &cache->key);
}
/* create a hashed filename from the key, and save it for later */
lockname = ap_cache_generate_name(r->pool, 0, 0, cache->key);
/* lock files represent discrete just-went-stale URLs "in flight", so
* we support a simple two level directory structure, more is overkill.
*/
dir[0] = '/';
dir[1] = lockname[0];
dir[2] = '/';
dir[3] = lockname[1];
dir[4] = 0;
/* make the directories */
path = apr_pstrcat(r->pool, conf->lockpath, dir, NULL);
if (APR_SUCCESS != (status = apr_dir_make_recursive(path,
APR_UREAD|APR_UWRITE|APR_UEXECUTE, r->pool))) {
ap_log_rerror(APLOG_MARK, APLOG_ERR, status, r, APLOGNO(00778)
"Could not create a cache lock directory: %s",
path);
return status;
}
lockname = apr_pstrcat(r->pool, path, "/", lockname, NULL);
apr_pool_userdata_set(lockname, CACHE_LOCKNAME_KEY, NULL, r->pool);
/* is an existing lock file too old? */
status = apr_stat(&finfo, lockname,
APR_FINFO_MTIME | APR_FINFO_NLINK, r->pool);
if (!(APR_STATUS_IS_ENOENT(status)) && APR_SUCCESS != status) {
ap_log_rerror(APLOG_MARK, APLOG_ERR, APR_EEXIST, r, APLOGNO(00779)
"Could not stat a cache lock file: %s",
lockname);
return status;
}
if ((status == APR_SUCCESS) && (((now - finfo.mtime) > conf->lockmaxage)
|| (now < finfo.mtime))) {
ap_log_rerror(APLOG_MARK, APLOG_INFO, status, r, APLOGNO(00780)
"Cache lock file for '%s' too old, removing: %s",
r->uri, lockname);
apr_file_remove(lockname, r->pool);
}
/* try obtain a lock on the file */
if (APR_SUCCESS == (status = apr_file_open(&lockfile, lockname,
APR_WRITE | APR_CREATE | APR_EXCL | APR_DELONCLOSE,
APR_UREAD | APR_UWRITE, r->pool))) {
apr_pool_userdata_set(lockfile, CACHE_LOCKFILE_KEY, NULL, r->pool);
}
return status;
}
